Radio tuning dial and means of mounting the same



Feb. as, 1928. 1,660,423

B. P. M KINLEY RADIO TUNING DIAL AND MEANS OF MOUNTING THE SAME Filed July 50. 1924 gwuemboz 351 7115 @btomwtyfi Patented I Feb. 28, 1928.

* UNITED stares v p reta n PATENT orric.

BENJAMIN P. MCKI NLEY, OF NEW YORK, N. Y., ASSIGNOR TO EEEMGO ELECTRIC MANU- FACTURING COMPANY, ENG, OF LONG ISLAND CITY, NEV] YORK, A GORPOllEtA'llION on NEW YORK.

RADIO TUNING DIAL AND MEANS or Moun'rriie THE SAME.

' Application filed July 30,

This invention relates to .index dials for use in connection with tuning condensers of radio receiving apparatus, and it is an object of the invention to provide an improved constructed and arranged dial of this character whereby it may be readily manipulated by the hand and fingers to facilitate the effecting of fine adjustments of tuning condensers.

Index tuning dials for this purpose are made of brittle material and are fixed to a shaft element of a. rotor member of the condenser, as by a set screw carried by or threaded into the material of the dial and adapted to oo-operate with the condenser shaft when mounted thereon to secure the dial in position on said shaft. However, due to the brittleness of the material of the dials great difficulty is experienced in threading the opening for the set screw. It is the usual practice in mounting an element of such materialupon an element by means of a set screw to embed a threaded member,

which is adapted for the engagement of a set screw, in the material as it is molded.

However, due to the construction and arrangement of index dials for radio tuning condensers this is not possible and therefore necessitates the arranging of the threaded member for the 'set screws in the dials after they are molded. I

It is an object of the present invention to overcome the above disadvantages and provide means for the engagement of a set screw and arrange the dial so that said means through the binding action of the screw upon the shaft of the tuning condenser will cooperate with the dial to lock it on said shaft.

In the drawing accompanying and forming a part of this specification, Figure 1 is a front elevation of a dial for radio tuning condenser or the like constructed and arranged in accordance with the present invention.

Figure 2 is a bottom view.

Figure 3 is a cross sectional view taken on the line 3-3 of Figures 1 and 2 looking in the direction of the arrows.

Figure 4c is a cross sectional view taken the line M of Figure 2 looking in the direction of the arrows; and t Figure 5 is a plan view on an enlarged scale of a disk portion of the dial to particularly show the construction and arrangement 1924. Serial no maoie.

tratedin the drawing comprises a disk portion 6 having a hollow knob 7 axially thereof and closed at the outer end, said knob being arranged with an inwardly extending axial hub 8 with a bore 9 extending thereinto from the inner end for the engagement of a shaft tomount the dial thereon, said shaft consisting of a part of the rotor of a tuning condenser of radio receiving apparatus. The hub 8 is of a length to extend beyond the inone hundred. i I

To facilitate the rotation of the disk an procure fine adjustments of the tuning condenser the knob and disk are arranged with beads 13 equidistantly spaced around the knob and extending longtiudinally thereof and continuing radially outward on the disk to adjacent the scale 12 with the portions of the beads tapering slightly outward; Interposed between each pair of beads is a series of knurls 14 extending in parallel relation to the beads with the knurls extending radially of the'disk tapering outward from the juncture of the disk with the knob as clearly shown in Figuresl and'5. By this arrangement a firm grasp may be had on the knob and assure rotation thereof by the slightest movement of; the hand or fingers, or the tips of the fingers may be pressed upon the knurls between the beads of the disk and the disk rotatably adjusted with equal facility. To reinforce the disk portion of the dial, theundersurfaceis provided with substantially equidistantly spaced ribs 15 extending from a point adjacent to where the knob extends from the disk to a circumferentially flattened portion 16, with ribs 17 of shorter length interposed relative to the ribs 155 '70 nor surface 11 of the peripheral portion of As stated dials for this purpose are made of a brittle material, such as bakelite, redmonal or condensite by molding under pressure and must be so arrangedth'at portionsv o'fthe dies may be withdrawn therefrom and the article withdrawn from other portions of the dies. Great difficulties has been experiencedin securely n'iounting said dialsupon the shafts of tuning condensers, since they must be securely fastened thereon and at the same time be readily releasable therefrom for making repairs or otherwise, and" for which purpose a set screw is utilized. Ow-

ing to the brittleness of the material the provision of a threaded borein which to mount 7 the set screw is a tedious operation. To obviate this one of a series ofribs 18 extending between the hub 8 and wall of the knob 7 is arranged with a double wall forminga recess between said walls, as clearly shown in dottedlines at 19 in Figure 3, witha portion thereof laterallyenlarged by recessing oppositewall portions of said recess, as at 20, to form a seat and abutment for a nut 21, a perforation 22' through the wall of the hub communicating with said nut seat and the bore in the hub, and there being arranged a perforation 23 in the wall of the knob in line with the hub perforation. To mount and lock the dial upon the shaft 10 the nut is inserted into its seat, and the threaded member, such as a headless set screw 24, is passed through the knob perforation 23 and threaded into the nut so that it will project partly into the hub perforation 22. This is done before the dial is placed upon the shaft. After the dial is .mounted upon the shaft it is locked thereto by entering a screwdriver through the knob perforation 23 to engar e the slot in the end of the screw and by rotating-the screw the end will abut against the shaft while the nut will be backed up or abutted against the shoulders formed by the lateral enlargements of the recess 19 to form the nut seat thereby firmly securing the dial to the shaft.

Tuning condensers usually comprise a series of segmental plates fixed in axial space drelation and a shaft mounted axially ofsaid plates'carrying complemental plates in interposed relation to the fixed plates and adapted to be variably'positioned by the shaft in relation to the fixed plates. It is essential that the dial be fixed upon the condenser shaft in predetermined position so that as the indices in connectlonwith the scale on the dial are brought in register with an index on the casing it will properly extending radially across said portion, as

shown at By pressinglthe tips of the fingers against said knurls25 and the thumb bearing on the knurls 14 extending longitudinally of the knob and continuing outward on the disk a very fine and ready adjustment of: the dial may be obtained, and thereby ob- Viating the necessity of utilizing a Vernier adjusting device as now is the case.

Having thus described my invention I claim r In a dial connection for radio tuning con densers, a diskhavi'ng an integral axial hollow knob closed at the outer endarranged with an integralhub extending axially in- .ward from the closed end of the knob and in spaced relationto the peripheral wall of theknob, said hubhaving abore; ribs ex tending radially between and merging with the hub and wall of the knob, one of said ribs being arranged with a radialrecess opening outward to the end of the hub and enlarged laterally in the direction of the axis of the hub atthe ijuncture of the rib withthe hub, the wall of the hub. having a perforation communioating with said enlarged portion of the recess; a nut in the ,enla-rgementpa threaded member in the recess having threaded engagement with the nutin the recess enlargement gand a shaft in the hub bore adapted to be engaged by said threaded member, and the wall of the knob having a perforation in line with the recess and perforationlin theihub for the passage of an implement to manipulate the threaded member.

signed at New York city in the county of New York and State of New York this 18th day of July A. I). 1924.

BENJAMIN P. MOKIN 

